Methods and apparatus for seating nonmagnetic articles in paramagnetic containers



July 9, 1968 F. G. LENTZ 3,391,517

METHODS AND APPARATUS FOR SEATING NONMAGNETIC ARTICLES IN PAHAMAGNETIC CONTAINERS I Filed May 26, 1966 I Nl/EN TOR E6. LENTZ atent Patented July 9, 1968 3,391,517 METHODS AND APPARATUS FOR SEATING N ONMAGNETIC ARTIQLES IN PARAMAG- NETIC CONTAINERS Forrest G. Lentz, Bethlehem, Pa., assignor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed May 26, 1966, Ser. No. 553,242 9 Claims. (Cl. 53-35) This invention relates generally to methods and apparatus for seating nonmagnetic articles in paramagnetic containers, and more particularly to the seating of fiat discs in close-fitting, open-topped cans. Accordingly, the general objects of the invention are to provide new and improved methods and apparatus of such character.

In the manufacture of certain types of semiconductor devices, such as transistors, it is necessary that a disc of a getter material be placed in an enclosed space be tween a header and a protective housing or can. Getter materials are those which absorb traces of free gasses, such as water vapor. The getter must be inserted in a flat position against the bottom of the can prior to welding the can to the header.

To provide a maximum amount of getter material within the enclosed space, the getter is customarily formed in the shape of a thin disc with an outside diameter slightly less than the inside diameter of the can. In the past, the getters have been deposited one at a time into a chute and allowed to freely fall into the cans; but the close fit of the getter disc within the can often resulted in the getter assuming a canted position in the can, which damaged the elements on the header when it was welded to the can.

Accordingly, another object of the invention is to provide new and improved methods and apparatus for seating a disc of getter material flat in the bottom of a close fitting transistor can.

A further object of the invention is to provide new and improved methods and apparatus for magnetically suspending and jiggling a container while it is advanced by a conveyor, particularly to assure seating of articles dispensed into the container.

With the foregoing and other objects in view, a method illustrating certain features of the invention includes the steps of advancing a paramagnetic container along a fixed path and dispensing a nonmagnetic article, such as a getter disc, into the container as it advances. Then, the advancing container is magnetically attracted and intermittently held to jiggle the container and thereby seat the article therein.

Preferably, the container is placed in a conveyor having a receptacle which supports the container as it advances. A magnet is positioned over the conveyor a distance which will allow the container to be attracted into proximity to the magnet, while still advancing with the conveyor. The article is dispensed into the container through a gravity chute having a portion of the chute passing through the magnet. The magnetic attraction continues to hold the advancing container and article with sufi'icient force that the container resists advancement by the conveyor. The container moves into a tilted position as the magnet attempts to hold the top of the container, while the bottom of the container continues being advanced by the convcyor. The tilted position presses the container into contact with the edge of the conveyor receptacle, which pushes on the side of the container and the portion of the container top surface in contact with the magnet. The push of the receptacle edge on the wall of the container overcomes the magnetic attraction and snaps the container into alignment with the receptacle and allows the full surface of the container to move back up into engagement with the magnet. This tilting and aligning action occurs repeatedly until the container advances beyond the influence of the magnet and jiggles the article sufiiciently to insure that it is seated on a flat side.

Other objects, advantages and features of the invention will be apparent from the following detailed description of a specific embodiment thereof, when read in conjunction with the appended drawings in which:

FIG. 1 is a perspective View of a getter disc and transistor can to be assembled;

FIG. 2 is a perspective view of a transistor header and the can to be assembled, showing the getter disc placed in the can;

FIG. 3 is a perspective view of the completed transistor; and

FIG. 4 is an elevational View, partly in section, illustrating one embodiment of method and apparatus for seating the getter discs in the cans in accordance with the invention.

Referring now in detail to the drawings, and particularly to FIGS. 1 and 4, the specific embodiment of the invention relates to the seating of a nonmagnetic getter disc 11 in a paramagnetic transistor can 12 by the use of a magnetic attraction unit 13. In one example the getter disc is composed of silica material.

As illustrated in FIGS. 2 and 3, the can 12 is later welded to a transistor header 14 to form a sealed transistor 16, including one of the getters 11 sealed within the enclosed space between the can and the header. The getter 11 must be inserted in the can 12 such that one of its flat sides 1'7-17 is seated against the bottom of 'the can 12. The other fiat side 17 is held in place after assembly by contacting terminal posts 18-18 of the transistor, as shown in FIG. 3. The cans are composed of a paramagnetic material, by which is meant one capable of experiencing attraction by a magnet. In one typical example the cans are composed of nickel. Each can 12 is formed with a cylindrical body 23 having a closed end 2 and a flanged lip 26.

As viewed in FIG. 4, a succession of the cans 1212 and getter discs 1111 are assembled by placing the cans, one at a time, on a conveyor 21 having a plurality of spaced receptacles 2222 for advancing the cans along a fixed horizontal path, from left to right in FIG. 4. The cans are retained in the receptacles 22--22 as the conveyor 21 advances, the cans being supported in the receptacles by gravity with the flanged lip 26 of each can contacting an upper surface 27 of the conveyor 21. The receptacles 2222 in this instance are circular bores in the conveyor, each defining a cylindrical wall 28 which urges the cans forward and an edge 29 at the intersection of each wall 28 with the conveyor surface 27. The diameter of each receptacle 22 is predetermined slight amount larger than the outer diameter of the cans. This difference in diameter allows the cans not only to be placed and retained in the receptacles, but also to move vertically out of the receptacles under the influence of magnetic attraction unit 13, preparatory to receiving a getter disc 11.

The getter discs are dispensed one at a time by a generally conventional dispensing mechanism 30 into the upper end 31 of a funnel-shaped gravity chute 32 and are allowed to fall through a discharge end 33 into the cans, as shown. The inside diameter of the discharge end 33 of the gravity chute 32 is approximately the same as the inside diameter of the can 12 in order to align the falling getter 11 with the can 12. In failing, the getter discs tend to tilt to allow the air to escape as they fall freely down from the chute 32. This increases the possibility of a getter disc assuming a canted position, such as indicated by the numeral 34, with respect to the bottom 2 of the can. The getter 11 can damage the terminal posts 18-18 and other elements on the header 14 in the subsequent welding operation if allowed to remain in the canted position 34.

The magnetic attraction unit 13 includes a flat, washershaped magnet 36 and a flat, nonmagnetic spacer plate 37 having a smooth contact surface and composed of a material such as aluminum. The magnetic attraction unit 13 is spaced above the conveyor 21 a predetermined distance X. The distance X must be set less than the height of the can 12 to allow a portion of the cylindrical side 23 to remain in contact with a portion of the inside wall 28 of the receptacle 22. The magnet 36 must be sufiiciently strong to attract the can 12 before and after the getter disc 11 is dispensed into the can 12 and must attempt to hold the can 12 from advancing with the conveyor 21. When the full surface of the flanged lip 26 on the can 12 is in contact with the spacer plate 37, the can 12 resists advancing and tilts into a position 38. When the can 12 assumes the tilted position 33 the edge 29 of the receptacle 22 pushes against the side 23 of the can 12 with a force sufiicient to overcome the attraction exerted by the magnet 36 on the edge of the lip 26 and snaps the can 12 back into alignment with the receptacle 22 and into full contact with the magnet spacer plate 37. As the can 22 is advanced by the conveyor 21, this tilting and aligning action is repeated to jiggle the can 12 and disc 11 to seat the disc 11 flat against the bottom of the can. As the can 12 advances beyond the influence of the magnet 36, the can 12 falls back into the receptacle 22 as shown at the right side of FIG. 4.

It is to be understood that the above-described embodiment is merely illustrative of the principles of the invention, and that other embodiments may be devised by persons skilled in the art which embody these principles and fall within the spirit and scope of the invention.

What is claimed is:

1. The method of seating a nonmagnetic article in a paramagnetic container, which comprises:

advancing the container along a fixed path in a conveyor having a receptacle therein for supporting the container;

dispensing the article into the advancing container; and

magnetically attracting and intermittently holding the container as it is advancing to jiggle the container and seat the article therein.

2. The method as recited in claim 1, wherein the article attracting and holding step is performed by holding the advancing container against a magnet with sufiicient attraction that the container attempts to resist advancing and tilts in the conveyor receptacle until a bind occurs between the points where the container contacts the conveyor and the magnet, whereupon the conveyor snaps the container forward into alignment with the receptacle and back into full contact with the magnet, this tilting and aligning action continuing until the container advances beyond the attraction of the magnet.

3. Apparatus for seating a nonmagnetic article in a paramagnetic container comprising:

a conveyor having a receptacle therein for supporting and advancing the container;

21 dispenser mounted over the conveyor for dispensing the article into the container; and

a magnet mounted over the conveyor to attract and intermittently hold the container as it is advancing to jiggle the container and seat the article therein.

4. Apparatus as recited in claim 3, wherein the magnet is mounted over the conveyor a distance which allows one end of the container to be attracted to the magnet and the other end to remain in contact with the advancing conveyor.

5. Apparatus as recited in claim 3, wherein the receptacle in the conveyor is of a size and shape to (a) support the container during advancement, (b) allow the container to rise into slidable proximity to the magnet, (c) advance the container during its proximity to the magnet, (d) allow the container to be tilted at an angle during advancement as the magnetic attraction holds the container with sufficient force that the container resists advancing, and (e) exert a forward force on the side of th container sufficient to overcome the magnetic attraction and snaps the container back into alignment with the receptacle and into full surface proximity to the magnet, whereby this tilting and aligning action jiggles the articles as the sequence of c, d and e is repeated untl the container advances beyond the attraction of the magnet and falls back into the receptacle.

6, Apparatus as recited in claim 5 wherein the dispenser comprises a gravity chute having an upper end into which the articles are individually fed and a lower end from which the articles are individually dispensed by gravity into each container, the lower end passing through an aperture in the magnet and terminating at the lower surface of the magnet '7. Apparatus as recited in claim 6, wherein the magnet is a fiat surfaced magnet lined with a fiat, nonmagnetic spacer plate, against which the container bears and along which the container rides when attracted by the magnet.

8. Apparatus for successively seating a plurality of nonmagnetic articles in a plurality of paramagnetic containers, which comprises:

a conveyor having a succession of spaced receptacles to support the containers for vertical movement and to advance the containers along a fixed horizontal path;

magnetic means for attracting the containers as they advance along the path to lift them partially out of the receptacles and hold them temporarily in slidable proximity to the magnetic means; and

means for dispensing the articles one at a time into the containers when the magnetic means is attracting them, after which the conveyor advances the containers past the magnetic means so that the containers fall by gravity back into the receptacles.

9. Apparatus as recited in claim 8, for seating a succession of flat, nonmagnetic discs on one of their flat sides in a plurality of open-topped paramagnetic cans, wherein:

the magnetic means comprises a flat-surfaced magnet lined with a flat, nonmagnetic spacer plate and mounted over the conveyor with the spacer plate facing the cans a distance such that the magnet will attract the cans and lift them partially out of the receptacles into sliding contact with the spacer plate, but still in contact with the conveyor, the magnet having sufiicient strength to hold the cans against the spacer plate and resist advancement by the conveyor;

the dispensing means includes a gravity chute mounted above the magnet, having an upper end into which the discs are individually fed, and having a lower end which passes through the magnet and spacer plate and through which the discs are individually dispensed by gravity into the cans; and

the conveyor receptacle size allows (a) each can in sequence to tilt as it resists advancing under the magnetic attraction, b) force to be exerted on the side of each can at the point of contact between the can and the edge of the receptacle as the can tilts to overcome the magnetic attraction exerted on the surface edge, and (c) the can to snap back into alignment with the receptacle and into full surface contact with the spacer plate.

References Cited UNITED STATES PATENTS Otto 53236 Polk et a1. 53l26 Tack.

Pitts 29-211 R. L. SPRUILL, Assistant Examiner. 

1. THE METHOD OF SEATING A NONMAGNETIC ARTICLE IN A PARAMAGNETIC CONTAINER, WHICH COMPRISES: ADVANCING THE CONTAINER ALONG A FIXED PATH IN A CONVEYOR HAVING A RECEPTACLE THEREIN FOR SUPPORTING THE CONTAINER; DISPENSING THE ARTICLE INTO THE ADVANCING CONTAINER; AND MAGNETICALLY ATTRACTING AND INTERMITTENTLY HOLDING THE CONTAINER AS IT IS ADVANCING TO JIGGLE THE CONTAINER AND SEAT THE ARTICLE THEREIN. 